Circulating Tumor Cells in Pancreatic Cancer: Current Perspectives

Abstract

Pancreatic cancer is the fourth leading cause of cancer-related death in the USA and Europe; early symptoms and screenings are lacking, and it is usually diagnosed late with a poor prognosis. Circulating tumor cells (CTCs) have been promising new biomarkers in solid tumors. In the last twenty years (1999-2019), 140 articles have contained the key words "Circulating tumor cells, pancreatic cancer, prognosis and diagnosis." Articles were evaluated for the use of CTCs as prognostic markers and their correlation to survival in pancreatic ductal adenocarcinoma (PDAC). In the final selected 17 articles, the CTC detection rate varied greatly between different enrichment methodologies and ranged from 11% to 92%; the majority of studies used the antigen-dependent CellSearch^© system for CTC detection. Fifteen of the reviewed studies showed a correlation between CTC presence and a worse overall survival. The heterogeneity of CTC-detection methods and the lack of uniform results hinder a comparison of the evaluated studies. However, CTCs can be detected in pancreatic cancer and harbor a hope to serve as an early detection tool. Larger studies are needed to corroborate CTCs as valid biomarkers in pancreatic cancer.

Keywords: biomarker; circulating tumor cells; liquid biopsy; overall survival; pancreatic ductal adenocarcinoma.

Figure 1

Schematic display of epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition (MET) in pancreatic cancer development. Circulating epithelial, circulating mesenchymal and circulating epithelial/mesenchymal cells are displayed to show the heterogeneity of circulating tumor cells (CTCs) (A). (B) shows the concept of early dissemination before malignancy. Mechanisms involved in this process are widely unknown and part of current research.